Proceedings. 239 



the existing substances, and, after vegetating for some 

 time, dies off, and thereby creates a fermentation of sugar. 

 This theory is a pathological one, according to which 

 it is not the normal productive yeast which acts, but the 

 dying one : that is, when it approaches its dissolution. Its 

 partisans claim that if sugar is consumed by the yeast and 

 alcohol ejected, then this action would be greatest when 

 it reproduces the most ; but this is not the case, for the 

 most alcohol is produced when the maximum reproduction 

 is passed. The author alluded as follows to the question 

 whether a ferment organism can change its physiologic;^! 

 action when placed under abnormal influence : — " I have made 

 some careful examinations in this direction, but cannot con- 

 scientiously affirm that the ferments sown in the liquids 

 were pure. For instance, if a quantity of starch or sugar, 

 and cheese or meat is sown with lactic ferment, butyric 

 acid is formed at the end of the reaction. If now we take 

 a trace of the butyric ferment out of the liquid, examine it 

 carefully under the microscope and perceive no other 

 ferment present, place it in a medium like the above, but 

 which has previously been heated so as to destroy the exist- 

 ing germs, then add the butyric ferment to the same, and 

 close the bottle with a cotton stopper, lactic acid is again 

 the first formed. Has then in this experiment the butyric 

 ferment changed into a lactic, or are the germs of the lactic 

 so small that, although present in the drop containing the 

 butyric ferment sown in the liquid, they escaped micro- 

 scopical detection? It seems to me that this question 

 can only be satisfactorily answered when an antiseptic 

 is discovered which has fatal effects on one and none 

 on the other. Pasteur's assertion that oxygen kills the 

 butyric ferment must still be taken with a grain of salt." 

 As regards the bearing of fermentation on technology, the 

 principal questions to be studied are, how to make the 

 mediums most suitable for the nutrition and multiplication 



